Speed-responsive deivce



Aug. 9, 1927.

Filed April 18. 1925 2 Sheets-Sheet 1 Aug. 9, 1927.

I E. c. VROMAN SPEED RESRONSIVE DEVICE Filed April 18. 1925 2 Spets+Sheet 2 2/2 'F Wm Patented Aug ,92 1,638,718 unw se sr'arss PATENTOFFICE;

ERWIN o. vnoman, or wA'rnRrowN',nnw YORK, ASSIGNOR and THE NEW YORK AIRBRAKE COMPANY,'A CORPORATION or vnew JERSEY.

srnnn-nnsronsrvn nnvrcE. Application filed April 18,1925 SerialNoi24,240.

ative without manipulation for either direction of travel of the engineor 'carxt o which it is applied and it mustrespond with considerableprecision. if annoying in tere'i'erences With train'movements are to .beavoided. Furthermore, it is desirable to apply such a switch directlytothe wheel or axle, and in such case the devicepis not spring borne andis necessarily subjected to severe shocks and to some exposure to theweather. Unless it isso designed thatfthe various contacts are relievedfrom wear as far as possible, accuracy cannotbe maintained.

Many mechanisms havebeen proposed and used experimentally, most of thembased on a centrifugal governing principle-4 Such devices have notproved satisfactory, first, because the action of the-governor isderanged by vibration.v inclination of the vehicle, and similar causes;and second, because the parts aresubjected to very severe wear. Suchwear is particularly pronounced in the case of brushes commonly usedwith rotating sliprings and commutators; So liar as This inventionrelates to'speed responsive electrical switches and particularly to aspeed responsive multiple "contact switch intended for use a part otanautomatic e control mechanism on railway trains.

- While many of, he features of the invention are applicable 'to thegeneral field'in which speed responsive switches maybe used, thisinvention involves certain features which particularly adapt it for usein the train control field and for thisireason a brief statement of therequirements in this field of use willbe given. 'lra-in controlmechanisms have been devised which produce applications of the brakesautomatically if the engineer passes a caution signal or a danger s nalset against him or it he exceeds a certain maximum speed. These systemsare objectionable because it is oc sionally necessary for a train topass a ca on signal andv enter a and it is entirely safe to do so prohetrainenters at a reasonable speed. rly it, isoccasionally necessary fora train to pass adan er sign'eland enter the danger l och, and entirelysafe to do devised which meets in a practical and sat- L so pro\.. .edthe train enters the block at a ist'act-ory manner the requirements ofthe reasonable speed. service. 7

Conscqiiently, s have been proposed which include a speed responsiveswitching? device tcd with hold-out mechanisms so contrived ti "i theengineer manipulates the caution herd-(mt mechanism when pass a cautionsignal, he may prevent an matic application oi the brakes it, and onlyii, the speed below a tired value determined by the setti oi the speedrespcmsive switch. A similararrangement is provided on the ;langcrorstop circuit, so that the engineer may pass a danger signal set againsthim if at the time passing he n'ianirnilates a corresponding hold-outdevice and if at the time the train is proceeding at a low speed (muchlower than that at which he is permitted to pass a caution signal), thisaction also being controlled-by aspeed responsive switch. The twofunctions can conveniently be secured by the use of two separate sets ofcontacts associated with a single speed responsive mechanism. A thirdcontact may be added tQ'tl-PPlY the brakes directly if the train speedexceeds some chosen maximum, regardless ofthe indications of the signalmechanism.

The speed responsive device must be operprinciples underlying theinduction type, calternating current motor. There is a rotratinglieldi'ormed'by plurality of per ma-nent magnets; there is an armaturemounted for limited rotation between limit stops andcarrying ashort-circuited winding; and there is a spring mechanism'which tends toretain the armature in a neutral or mid-position. The rotation of thefield magnets in either direction exerts a-turn ing moment on thearn'ieture and swingsit in one or the other direction through a variableangle depending on the direction and rate of rotation of the field.

The armature carries a specially shaped insulated contact on which bearthree brushes, each controlling a corresponding one of the threecircuits above alluded to, and a fourth brush connected to a commonreturn-for such three circuits. This contact is so shaped'thatthe threecircuits are interrupted successively at proper speed intervals.

It hasbeen found in devices of this sort that while the torque exertedby the field on the armature as a result of speed varia- I am aware, nodevice has heretofore been.

The invention makes use of the general I tions varies quite decidedly inthe lower ranges, the variation at the higher s eed range is less.Consequently it is desirab e to provide a secondary torque-transmittingmeans having a critical point at which such seconda -means comessuddenly into action at the highest or limiting speed.

Hence the reaction between'the field and the armature is used to actuatethe caution and danger contacts, and a centrifugal friction device isprovided which at the maximum speed produces frictional engagementbetween the field and the armature, and thus suddenly produces theadditional torque necessary to move the speed limiting brush off thearmature contact. In this way I combine the smoothly graduatedcharacteristic of the electro-magnetic action throughout the normalspeed ranges with sudden and pronounced responses at a maximum speed.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which:

Fig. 1 is a vertical axial section showing the complete device as itappears attached to a pony truck wheel;

Fig. 2 is a section on the line 22 of Fig.

1 with certain portions broken away; Fig. 3 is an enlarged fragmentarysection on the line 33 of Fig. 2, showing the construction of thefrictional mechanism which acts to connect the field and the armature atthe critical maximum speed.

A portion of the hub of a pony truck wheel isshown at 6 in dotted lines.To this is connected'by means of machine screws 7 an adapter 8 whoseform is dependent on the size and form of the truck wheel. The purposein using the adapter is to permit the standardization of all other partsof the device according to principals well understood by those familarwith machine design. The adapter 8 receives directly the base plate 9 onwhich seats a cover 10, and the adapter base and cover are connectedtogether by a series of machine screws 11. All these parts areconstructed of brass.

Directly mounted on the base plate 9 by means of a plurality of machinescrews 12 is a circular series of V-shaped permanent magnets 13. Thearrangement of these magnets is clearly shown in Figs. 1 and 2, and theyform a complete circle except that one magnet is omitted from the seriesto give space for the frictional device, clearly shown in Figs. 2 and 3.This consists of a guide member 14 held to the base 9by means of a capscrew 15 and provided with a guide-way in which there slides, in adirection radial to the base 9, a plunger 16 having a head or brake shoemember 17 at its outer end. A machine screw 18 whose end engages in aslot or key 19 on the plunger 16 prevents rotation of the plunger 16- inthe guide 14.

The plunger is urged radially inwards by means of a coil spring 20 whichsurrounds it and which seats against a washer 21 adj ustable on theplunger 16 by means of a nut 22 and a check nut 23:

At the center of the base plate 9 there is a circular aperture and anadjacent seat for the outer race of an annular ball bearing indicatedgenerally by the numeral 24. At the center of the cover 10 there is alsoan opening provided with a seat for the outer race of a similar annularball bearing indicated generally by the numeral 25. This race is held inplace by means of an annular plug 26. The inner races of the bearings 24and 25 are fixed on a shaft 27. The inner race of thebearing 25 ismounted directly onthis shaft, while the inner race of the. bearing 24is fast on a collar 28 which in turn is fast to the shaft.

There is a dust guard 29 between the collar 28 and the base 9. There isa dust guard 30 between the annular plug 26 and the shaft 27, andanother, 31, between a collar 32 fast on the shaft 27 and the cover 10.A cap plate 33inounted on the base 9 covers the end of shaft 27 and withthe dust guard 29 encloses the ball bearing 33.

The base 9 and its connected parts rotate with the wheel 6, and shaft 27is held at rest by means of an angle fitting 34 screwed on its outerend, the fitting 34 being connected by a nipple 35 with a short lengthof stiff rubber hose 36 whose upper cnd'is connected to a part of theframe of the vehicle (not shown). The hose 36 and fitting 34 serve as aconduit for electrical wiring connections, hereinafter described, andthe hose retains the shaft 27 against rotation and at the same timepermits minor movements, incident to vibration and the like, which areunavoidable under practical operating conditions.

Mounted on the shaft 27 between the bearings 24 and 26 are two annularball bearings 37 which carry a hub 38. Locked to the hub 38 by means ofa threaded clamp ring 39 is a cup-shaped armature 40 of magneticmaterial whose rim surrounds the pole pieces of the magnets 13, therebeing a small air gap, approximately .015 inches. To one side of themagnets the armature 40 carries a single short-circuited winding in theform of a copper ring 41. This is held in place by a series of rivets 42and is insulated from the armature 40 by means of a thin strip ofinsulation 43 underlying the windings and by bushings 44 completelysurrounding the rivets.

Locked on the shaft 27 by means of a threaded sleeve 45 is a contactcarrier'plate 416. This is provided at its lower end with a stop lug 47which coacts with two stop pins 48 on the armature 40. Near end itcarries four aligned contact fin em 49, 50, 51 and 52 all insulated fromthe plate its upper 4:6 and all having their effective contact points ina straight line. These contacts 49 to 52, inclusive, bear against acontact plate 53 which is mounted in a bed of insulation 54 carried onthe armature 10, so that except for the contacts 49 to 52, inclusive,the contact 53'is completely insulated.

When the vehicle is at rest, the armature stands so that the lineconnecting the contact points of the contacts 49 to 52, inclusive,coincides with. the center line of the contact 53. The margins of thecontact 53 are so shaped that the contacts 49, 50 and 51 pass clear ofthe contact 53 successively in the same se uence and for the samedisplacements of the armature lO, clockwise or counter-clockwise, fromits normalzero position, shown in Fig. 2} The arn'iature is constantlyurged towards this position by a double spring structure mounted chieflyon the armature 10 and reacting with portion of the plate at which,being carried by the shaft 27, is fixed in position.

There is a spring housing 55 which has threaded extensions 56 at its twoends.

These pass through lugs 57 on the armature 40 and may be adjustedtherein by means of opposed nuts.58. The housing 55 has within its endsspring seats to receive two opposedcoil springs 59 whose inner ends bearon a thrustblocl; G0 guided ina radial slot on the plate 46.Consequently, the armature 40 may rotate in either direction againstresistance by one or the other of. the springs 59 and the zero orneutral position of the armature may be fixed by adjustingthe nuts 58.The movement of the armature in; each direction i limited byacorresponding one of the two pins 48 which collide with the stop lug 47.1

There are individual electrical connections 61, 62. 63 and 64: for thefour contact fingers 49 to 52, inclusive, and these extend through apassage 65 formed in the shaft 27 to receive them.- This passage leadsto the end of the shaft so that the connections pass off through theangle fitting 3% and the hose 36. The contact 4.9 is the one whichclears the contact atthe lowest speed. Hence in a stop mechanism suchasdescribed it would control he danger hold-out circuit. Contact 50 isthe next to clear and therefore controls the caution hold-out circuit.Contact 51 is the last to clear and directly controls a train stopmechanism, usually one which applies the brakes. Contact 52 is merelythe common return contact for the other three. After the contacts 49 and50 have cleared the contact 53 and just as the critical speed isreached, the plunger 16 will have moved out under centrifugal force farenough to move the brake shoe 17 into contact with the inner face of thearmature 4:0. The additional force thus imposed on the armature ringshifts it far enough to clear the contact 51. At all low speeds theplunger 16 and its brake shoe are ineffective.

he operation of the device will be readily understood from thedescription already given. It will be observed that the mechanism issimple and rugged in construction; that those parts which are inconstant motion are mountedon ball. bearings; and that the brushes aresubject only to such wear as is occasioned by, motion of the armatureinci dent to spcedchanges. The device responds in the same manner,regardless of the direction of rotation of the wheels, and its responsemay readily be adjusted bychanging the form of the contact 53 and bychanging the stiffness of the springs 59, either or both, as may befound convenient. The use of the centrifugal plunger l6 permits a sharpresponse of the device to the critical maximum speed, while permittingadvantage to be taken of the flexibility and smooth actioncharacteristic of the reaction between the armature and the field. Thiscritical response readily adjustable. Finally, thedevice completelyhoused against the= weather and is adaptable to existing equipmentwithout substantial change therein.

Obviously various structural changes are possible and I do not limitmyself to the specific structure except to the extent speciiied in theclaims.

nt features of thcinvention are in, per t riimiing balance and so thatit operates 'in the same characteristic. manner in both directions ofrotation. To secure this retailt the simplest arrangement isto make thecontact 53 syn'imetrica-l with respect to a line radial to the armatureand to cause the contacts 49 to 52, inclusive, to contact along thisradial axis ofsymmetry when the device in its normal neutral ormid-position. The exact shape of the contact 53 is a function of thearrangement of the contacts 4:9 to 52, inclusive, of the speeds at whichthe various controls are to be effective,

and of the motion characteristic of the armature 40 under varyingspeeds.

hat is claimed is:

1. ii speed responsive device comprising in combination a rotatablefield member a rotatable armature member associated therewith; means forrotating one of said members in either direction at variable speeds;yielding means arranged to permit limited rotary displacement of theother of said members conforming in direction and extent with thedirection and speed of rotation of the first'member; and a series ofelectric switch contacts arranged to be successively opened and closedin a chosen order by the displacement of said other member in eitherdirection relatively to its normal position.

2. A speed responsive device comprising in combination a rotatable fieldstructure; a

igement of the device so that it is .J

ill)

rotatable armature associated therewith; means for rotating said fieldstructure in either direction atvariable speeds, yielding means arrangedto permit limited rotary displacement of the armature conforming indirection and extent with the direction and speed of rotation of thefield structure; and a series of electric switch contacts arranged to besuccessively opened and closed in a chosen order by the displacement ofsaid armature in either direction relatively to its normal position.

3. A speed responsive device comprising in combination a rotatable fieldstructure; a rotatable armature associated therewith; means for rotatingsaid field structure in either direction at variable speeds; yieldingmeans arranged to permit limited rotary displacement of the armatureconforming in direction and extent with the direction and speed ofrotation of the field structure; a contact mounted on said armature, thecon tour of said contact being symmetrical with reference to a lineradial to the armature; and a series of contacts bearing on said arniaturecarried contact in a line which, in the neutral position of thearmature, coincides with said radial line.

4. A speed responsive device comprising in combination a rotatable fieldmember; a rotatable armature member associated therewith; meansforrotating one of said members at variable speeds; yielding meansrestraining the other of said members and arranged to permit rotarydisplacement thereof to an extent conforming to the speed of rotation ofthe first member; and a centrifugal brake device arranged to operate ata critical speed to connect said members frictionally.

5. A speed responsive device comprising in combination a rotatable fieldmember; a rotatable armature member associated therewith; means forrotating said field member in either direction at variable speeds;yielding means arranged to permit limited rotary displacement of thearmature member, conforming in direction and extent with the speed anddirection of rotation of said field member; and a centrifugal brakedevice re sponsive to the speed of said field member and arranged toestablish a frictional connection between said members when said fieldmember attains a chosen speed. i

6. A speed responsive device comprising in combination a rotatable fieldmember; a rotatable armature member associated therewith; means forrotating one of said members in either direction at variable speeds;yielding means arranged to permit limited rotary displacement of theother of said members conforming in direction and extent with thedirection and speed of rotation of the first member; a centrifugal brakedevice arranged to come into action at a critical speed and establish africtional connection between said members; and a series of electricswitch contacts arranged to be successively opened and closed by themovements of said other member, the actuation of the last contact of theseries being effected at said critical speed by said frictional device.7. A speed responsive device comprising in combination a rotatable fieldstructure; a

rotatable armature associated therewith; means for rotating said fieldstructure in either direction at variable speeds; yielding meansarranged to permit limited rotary displacement of the armatureconforming in direction and extent with'the direction and speed ofrotation of the field structure; a centrifugal brake device interposedbetween said field structure and armature and arranged to come intoaction at a critical speed to establish a frictional driving connectionbetween said ,field structure and said armatiiire; a contact membermounted on said armature and having a contour symmetrical with referenceto a line radial to said armature; and a plurality of contact membersengaging said contact member in a line which, in the neutral position ofthe armature, coincides with said radial line, the parts being soarranged that the brushes clear said contact successively as thearmature is displaced from its neutral position and the last brush isabout to clear said contact as the field approaches said critical speed.

In testimony whereof I have signed my name to this specification.

ERV IN C. VROMAN.

